1. Field of the Invention
This invention relates to mobile, microphone-transmitter assemblies.
2. Description of the Prior Art
Various mobile, microphone-transmitter assemblies are found in the prior art. Some are referred to as cordless, self-contained microphone transmitters (see U.S. Pat. No. 3,564,416), microphone transmitter having a lavalier type antenna (see U.S. Pat. No. 3,134,074) and wireless loudspeaking telephones (see U.S. Pat. No. 3,124,657). Each of these and similar arrangements transmit radio frequency signals which are received by base stations. There are, however, several disadvantages to transmitting radio frequency signals. Firstly, they require some sort of antenna structure. Secondly, they may interfere with one another or other electronic apparatus located in adjacent rooms or offices.
Another form of wireless communications which overcomes the above disadvantages uses infrared energy. Stereo sound systems having infrared transmitters at their base stations and infrared receivers in headphones have been built, for example, so that a user may move relatively freely about a room and still appreciate the stereo effect (see U.S. Pat. No. 4,068,093). Furthermore, television receivers having infrared transmitters at their picture tube locations and infrared receivers in headphones have been built so that television sound may be heard by a viewer without the sound disturbing the other household members.